1. Field of the Invention
This invention relates generally to methods of orienting an easy axis of a high-aspect-ratio pole piece of a magnetic write head, and more particularly relates to methods of making a magnetic write head which include forming a pole piece over a substrate and applying a magnetic field to a pole tip of the pole piece in a direction forming an angle that is out-of-plane from the substrate and in-plane with a side wall of the pole piece which vertically projects from the substrate.
2. Description of the Related Art
Computers often include auxiliary memory storage devices having media on which data can be written and from which data can be read for later use. A direct access storage device (disk drive) incorporating rotating magnetic disks are commonly used for storing data in magnetic form on the disk surfaces. Data is recorded on concentric, radially spaced tracks on the disk surfaces using a magnetic head which is formed of pole pieces. A read sensor of the magnetic head is used to read data from the tracks on the disk surfaces.
Traditionally, write heads were formed with pole pieces having heights that were less than their widths. Today, for achieving much greater track densities (i.e. greater tracks per inch or TPI), pole pieces are formed having heights that are greater than their widths. For example, the height-to-width ratio of today's pole tips may be greater than four-to-one (4:1). Such write heads are said to have a “high-aspect-ratio”. It has been discovered that conventional magnetic field plating/annealing does not properly set the “easy axis” of pole tips having such high-aspect-ratios. Stress in such pole tips materials is high which causes stress-anisotropy in the pole tip region. The stress-induced Hk has been estimated to be about 100 Oersteds in an unfavorable orientation that is perpendicular to the ABS and essentially collinear with a driving field of the write head (which corresponds to a uniaxial anisotropy constant of about 80e3 erg/cm3 for materials having a saturation magnetization Ms of about 2 Tesla). With the overall easy axis dominated by stress in such unfavorable orientation, switching speed is reduced and is relatively slow since the initial torque exerted by the driving field is small on the magnetization due to the relatively small angle between the field and the magnetization.
What are needed are methods of orienting an easy axis in today's pole pieces to improve writing efficiency.